add http put event

covas_mobile/lib/classes/eventAdded.dart

@@ -0,0 +1,31 @@
+import 'package:flutter/material.dart';
+
+import '../main.dart';
+
+mixin ShowEventDialog<T extends StatefulWidget> on State<T> {
+  void showEventDialog(BuildContext context, String text) {
+    // Create AlertDialog
+    AlertDialog dialog = AlertDialog(
+      title: Text("Evenement ajoute"),
+      content: Text(text),
+      actions: [
+        ElevatedButton(
+            child: Text("OK"),
+            style: ElevatedButton.styleFrom(
+                padding: EdgeInsets.symmetric(horizontal: 50, vertical: 20),
+                textStyle:
+                    TextStyle(fontSize: 15, fontWeight: FontWeight.normal)),
+            onPressed: () {
+              Navigator.of(context).pop("Yes, Of course!"); // Return value
+            }),
+      ],
+    );
+
+    // Call showDialog function to show dialog.
+    Future futureValue = showDialog(
+        context: context,
+        builder: (BuildContext context) {
+          return dialog;
+        });
+  }
+}